I just read a book about divorce and it stated make your child arrangements and dealings with ex like a business arrangement. Use your own judgement as to what your ex knows. I think it is easier if the ex is far away. Also, important to give him every chance to be involved with the kids and document it; that way he can never say you didn't let him know in advance. In my state, both parents have to attend a parenting class before divorce and a parenting plan is lined out and filed as part of the divorce. Hope this helps.